/**
 * @Author: XXHH
 * @CreateTime: 2025-06-08
 */
public class Demo47 {
    public static void main(String[] args) {
        StringBuffer content = new StringBuffer();
        content.append('a');
        content.append('b');
        content.append('c');
        content.append('d');
        System.out.println(content.toString());
    }
}
